Incidence of left atrial thrombi in patients with atrial fibrillation and low thromboembolic risk: do we always need transesophageal echocardiography before rhythm control therapy?

Abstract Background Oral anticoagulation (OAC) therapy is a cornerstone in the treatment of patients with atrial fibrillation (AF) who are at an increased risk for thromboembolic events. However, guidelines recommend performing a transesophageal echocardiography (TEE) to rule out intracardiac thrombi in patients who are not on adequate OAC therapy prior to an intended rhythm control therapy, regardless of clinical risk category. Purpose Aim of this study was to investigate the prevalence of abnormal TEE findings in patients with low thromboembolic risk and to identify predictors for such pathologies. Methods In this monocentric, retrospective, cross-sectional cohort study, we examined digitalized clinical routine data from electronic medical records of our Heart Center between January 1, 2010, and December 31, 2022. Adult AF patients with a low thromboembolic risk according to a CHA2DS2-VA score of 0 that underwent TEE for any reason were included. Patients who had previously undergone any intervention aimed at closing the left atrial appendage were excluded. Primary endpoint was the detection of left atrial thrombi by TEE. Secondary endpoints included the prevalence of any TEE-related abnormalities. Results In total, 701 patient cases from 602 individual patients (median age 52 years, 4.7% female, median Elixhauser comorbidity index 0) were included. TEE was performed prior to an intended rhythm control therapy in 97.9% of cases. OAC was considered sufficient in only 16.4% and 72.5% had ongoing atrial arrhythmia at the time of TEE. Left atrial thrombus was detected in only one individual (0.1%) who was in sinus rhythm with signs of advanced electrical remodeling in baseline ECG. Intraatrial sludge and an impaired flow velocity in the left atrial appendage were found in another 11 and 27 cases. A lower eGFR and a higher body mass index were independently associated with the prevalence of any prothrombotic abnormalities in TEE in multivariable analysis. Except for the patient with solid atrial thrombus, the intended rhythm control therapy was performed in all patients without any adverse events in short-term follow-up. Conclusion Our study revealed a low rate of TEE-associated pathologies in AF patients with low thromboembolic risk. We identified additional risk factors that can complement the conventional clinical scoring. Further scientific evaluation is required to determine if TEE can be dispensed within selected subgroups in the future.